http://www.comicartfans.com/GalleryPiece.asp?Piece=958604&GSub=138115Cosmic Crossover Special #1 (January, 1965)
Co-Publishers: DC, Marvel, Standard
Writer: Some Hack
Released around October, 1964 this Silver-Age tale unites the premiere super-teams of the Justice League of America (then on issue 33), the Sentinels (#35), and newcomers, the Avengers (on iissue 12) for the first time. And all for only 25 cents!! On television, another team called the Avengers enjoyed great popularity, Gunsmoke was entering its 10th season, and the Rolling Stones debuted on the Ed Sullivan Show.
Splash Page:
Kang and the Lord of Time traverse the same space-time co-ordinates (at the same time!(?) - it's comics in the 1960s, it can totally happen) and the resulting crossing of the time streams (and travellers and machines) enables them to discover the ability to cross from one parallel universe to another (really, what the heck's the difference between parallel universes and divergent timelines?). Cyborilla's recent experiments in time viewing alerted him to their actions and he contacts them both via his viewer. Together they hatch a plan to rule the Earths of each others' dimension (i.e. Kang takes over the Standard Comics Universe, Cyborilla takes DC, and Lord of Time gets Marvel).
They recruit some of their fellow villains (two from each Universe, I guess they were trying to save money) to eliminate the premiere superhero teams from each Universe. Catching the heroes unaware, the villains defeat the heroes and exile them to Limbo, between the Universes.